This invention relates to the preparation of carboxylic acid salts, and more particularly, relates to a method for the preparation of carboxylic acid salts by the reaction of primary alcohols with a hydroxide base in the presence of a novel catalyst. The invention also relates to the preparation of the catalyst and compositions thereof.
Carboxylic acid salts are useful in various applications. The salts can be neutralized to the corresponding acids which are also useful in a number of applications, such as a material for pharmaceuticals, agricultural chemicals, pesticides and the like or precursors thereof. Many of such carboxylic acids are available commercially in large quantities.
U.S. Pat. No. 4,782,183 to Goto et al. discloses a method for the manufacture of amino carboxylic acid salts which comprises contacting an amino alcohol with an alkali metal hydroxide in the presence of a Raney copper catalyst, or a copper catalyst supported on zirconium oxide.
U.S. Pat. No. 4,810,426 to Fields et al. discloses a process for the production of N-phosphonomethylglycine by oxidizing N-phosphonomethylethanolamine, or the cyclic internal ester thereof, with an excess of an aqueous alkali and in the presence of a copper catalyst, and thereafter, heating at a temperature between 200.degree. C. and 300.degree. C. The resulting salt is neutralized with an acid to produce the desired N-phosphonomethylglycine.
U.S. Pat. No. 5,292,936 to Franczyk discloses an improved process to prepare an amino carboxylic acid salt. According to the process, an aqueous solution of an amino alcohol is contacted with an alkali metal hydroxide in the presence of an effective amount of a Raney copper catalyst that has from about 50 parts per million to about 10,000 parts per million of an element selected from the group consisting of chromium, titanium, niobium, tantalum, zirconium, vanadian, molybdenum, manganese, tungsten, cobalt, nickel and mixtures thereof.
Although satisfactory results are achieved by the processes of the prior art to convert an alcohol to a carboxylate using a copper catalyst, or even a Raney copper catalyst, it has now been found, in accordance with the teachings of the present invention, that the novel catalysts of the present invention can be used to convert an alcohol to the corresponding acid salt in a shorter period of time than with the use of other copper catalysts, including Raney copper catalysts. This results in significant capital savings and operating costs, when such reactions are practiced on a commercial scale.
The journal article "Dependence of Selectivity on the Preparation Method of Copper/.alpha.-Alumina Catalysts in the Dehydrogenation of Cyclohexanol" by Hsin-Fu Chang et al., Applied Catalysis A: General, 103 (1993) 233-242 discloses an electroless copper plating method, a precipitation method and an impregnation method in the preparation of eleven copper/.alpha.-alumina catalysts. The effects of the method of preparation on the dehydrogenation reaction of cyclohexanol were investigated. The reported results showed that the dehydrogenation activity increased as the copper loading increased up to a certain limit, and then declined with further copper loading.